<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

  <input id="inputEL" class="" type="text" name="" age="20">
  <script>
    // function HTMLInputElement() {
    //   this.id = 'inputEL'
    //   this.type = 'text'
    //   this.placeholder = ''
    // }
    // const inputEL= new HTMLInputElement();
    const inputEL = document.getElementById('inputEL');
    console.log(inputEL.id);
    console.log(inputEL.type);
    console.log(inputEL.placeholder);// ''
    console.log(inputEL.age);//undefined

  </script>
</body>

</html>